The robbers opened fire at passengers when they tried to resist the robbery attempt on the Muzaffarpur-Gorakhpur passenger train near the Sugauli railway station, some 200 km from here, Muzaffarpur Superintendent of Railway Police Shiv Kumar Jha told IANS over telephone.

According to passengers, there was no police escort team on the train at the time of the incident.

"We have started a probe into the incident and will take action against officials found guilty of negligence of duty," Jha said.

The injured passengers were admitted to the railway hospital for treatment, he said.

The robbers escaped from the train after pulling alarm chain, police officials in Motihari said.

A first information report has been lodged at the government railway police station in Motihari.